Hydraulic tubing connector with vibration damping means



April 28, 1970 D V N RC. HYDRAULIC TUBING CONNECTOR WITH VIBRATIONDAMPING MEANS Original Filed June 2'7, 1966 Strain Gauge Ill/IE inventory -X l2 m. m V n r H o u A S f D l r 6 .D r e H United States Patent26,870 HYDRAULIC TUBING CONNECTOR WITH VIBRATION DAMPING MEANS HerbertD. Sullivan, Chicago, Ill., assignor to International Harvester Company,Chicago, III., a corporation of Delaware Original No. 3,400,953, datedSept. 10, 1968, Ser. No. 560,766, June 27, 1966. Application for reissueMay 14, 1969, Ser. No. 830,902

Int. Cl. F16l11/12, 13/04 US. Cl. 285-50 2 Claims Matter enclosed inheavy brackets appears in the original patent but forms no part of thisreissue specification; matter printed in italics indicates the additionsmade by reissue.

ABSTRACT OF THE DISCLOSURE A hydraulic tubing connection having a fluidcarrying tube enclosed within a support tube, a connecting tube, a metalto metal sphero-conical seal connecting the fluid carrying tube to theconnecting tube, and a resilient packing between the fluid carrying tubeand the support tube spaced from the connection a distance equal to atleast one and a half outside diameters of the fluid carrying tube.

This invention relates to a connector between several tube sections of ahydraulic line and/or between a tube section and another element of anhydraulic circuit.

A general object of the invention is to provide a novel, simple andeffective connection for tubes or conduits of a hydraulic line orbetween a line and a component, such as a pump, which effects a goodseal and wherein the parts are so arranged as to effectively minimizefatigue failures at the seal connection.

In hydraulic lines which are subjected to extremely high normalpressures, such as about 5,000 p.s.i. and wherein surge pressures mayreach 8,000 p.s.i. or over, it has been found that resilient sealingconnections are ineffective. The high pressures cause the tubing to actas cylinders if the seals hold and thus the tubing parts. Variousattempts have been made to prevent such separation even to the extent ofproviding sharp points on the nut embracing the tubing at the connectionso that the points dig into the tubing wall as the tubing is beingforced out of the nut. However, under the high pressures encountered,even such structures fail since these points have been known to scarfout the tubing wall and the tubing separates anyway. Making the tubingof special hard steels defeats the purpose of the points since theycannot penetrate. The only alternative is to have a metal-tometal sealby a spherical sealing ring integrated with the tube and clamped withincomplementary cones or by flared fittings. Further, these same highinternal pressures necessitate the use of heavy wall tubing. Thereinlies the problem with all known high pressure connectors. Given a rigidsealing joint and rigid tubing and add vibration to the tubing and anideal condition prevails for fatigue failure at or near the terminal endof the tube.

The invention contemplates a novel, firm self-centering supportextending from a pump, motor, or other component to which the hydraulicline is connected.

A more specific object of the invention is to provide a connection in ahydraulic circuit between components, such connection comprising ametal-to-metal contact between the connecting parts so as to effect ahigh pressure seal therebetween and wherein means are provided forpreventing relative movements therebetween at the metalto-metal areasand wherein a supplementary support is provided remote from the sealingarea.

Re. 26,870 Reissued April 28, 1970 A more specific object of theinvention is to provide novel connections as set forth which aresubjected to vibrations, said connections comprising a sleeve membersleeved over the end of one tube which is provided with a sealing meansat one end engaging a generally conical seat within the sleeve, thesleeve including a nut-type packing gland which is spaced axially fromthe sealing means such as a ring or flare, the packing gland serving toaccommodate relative angular movement between the sleeve and the tubewith a damping action of an elastomer ring interposed between the sleeveand the tube and the sleeve being connected and in effect forming partof the component to which the tube is connected.

A further object of the invention is to provide a connection betweensections of hydraulic lines wherein the lines or sections of lines areaccommodated angular displacement between and wherein the connectionresiliently dampens relative movements between these parts.

These and other objects and advantages inherent in and encompassed bythe invention will become more readily apparent from the specificationand the drawings wherein:

FIGURE 1 is an axial sectional view of the novel connection;

FIGURE 2 is a transverse sectional view thereof taken substantially online 2--2; and

FIGURE 3 is a view similar to FIG. 1 illustrating the test procedureinvolved.

Describing the invention in detail and having particular reference tothe drawing there is shown a conduit line generally designated 2 whichincludes a pair of axially spaced tube sections 3 and 4 which arearranged in endto-end relationship and interconnected by the novelconnector generally designated 6. The connector 6 includes a sleeve (ornut) 7 which is telescoped over the end portion 8 which extends througha bore 10. The tube 3 is provided with a spherical sealing ring 12 atthe terminal edge 14, said spherical ring 12 having a cylindrical bore16 which snugly fits over the periphery 18 of the tube 3 and is thereateither weld connected or sweated on and secured as by solder as wellknown to those skilled in the art. The ring 12 has a Spherical outersurface or contour 20 which engages on its inner side as at 22 with aconical surface 24 which is formed within the tube 7 intermediate itsends at the inner extremity of an enlarged bore portion 26 at one end ofthe tube whereat there is admitted a sleeve or nipple portion 28 of anipple generally designated 30. The nipple portion 28 at its inner endis provided with a conical internal edge 32 which engages the sphericalsurface 20 as at 34. The portion 28 of the nipple 30 is threaded as at38 which inter threads with threads 40 on the interior of the enlargedbore portion 26 whereby upon the nipple portion 28 being threaded intothe enlarged bore 26, the bearing surface 34 will engage the surface 20as at 32 and will then urge the ring 12 into engagement as at 22 withthe conical shoulder 24. Thus, it will be seen that a universalconnection is developed between the sleeve 7 and the nut portion 30 andthe pipe or tube 3 so that they do not have to be in true alignment.

The tube 8 has its periphery 18 spaced radially inwardly from the boresurface 10 and at an axially displaced area with respect to the ring 12is engaged by a ring 46 of elastomer material. As well seen in FIGURE 1,the ring of elastomer material may be split diagonally with respect tothe axis of the connection or the tube and at its inner edge 48 mayengage the opposite or opposing edge 50 of the sleeve and at its outeredge 52 may engage an internal flange 54 of a nut 56, the nut 56 havingan axial p rtion 58 which has an internal bore 60 threaded as at 62which in turn is threaded on the thread 64 which is formed on thereduced end portion 66 of the sleeve 7. Thus, it will be seen thattightening of the nut 56 will compress and distort the sealing gland 46thus will cause the material of the packing gland to flow radiallyinwardly and yieldably engage the periphery 18 of the tube or conduit 3.Thus, it will be seen that the conduit portion 3 is rigidly clampedthrough ring 12 to the shoulders 24, 34 and that flexing movement of thetube is yieldably controlled by the elastomeric ring 46. It will benoted that the coupling sleeve or nut 30 may be provided with anhexagonal wrench-engaging portion 56 intermediate its ends and that theouter end portion 68 of the member 30 may extend axially outwardly ofthe portion 56 and be externally threaded as at 70 in order to threadinto complementary thread 72 on the interior of the conduit section 4.This section 4 may be part of a pump housing, motor, etc. Thus the nut56 and sleeve 7 form in effect a rigid part of the structure 4 and thepacking gland 46 provides an auxiliary support for tube 3.

Thus, a novel, simple, and effective connection has been provided whichaccommodates relative angular displacement between the sections of theconduit so that they need not be stressed into alignment and also theconnection distributes vibration induced stresses over a length of tubesuch as reduces these stresses to a nondestructive level.

We have found from extensive tests that a critical relationship existsin the disposition of the elastic gland with respect to the sphericaljoint otherwise the connection quickly fatigues and fractures. It hasbeen found that the span from the center of the rigid sealing joint tothe center of the elastic gland must be at least one and one halfdiameters of the tube 3 being connected for effective vibrationisolation. The following calculations are representative:

MATERIAL Three fitting nuts 7 for spherical ferrule 1-inch tubefittings. (1) production 2 length, (2) special 1 /5" length and (3)special 1%" length.

METHOD A 4-foot length of 1010 steel tubing 1-inch OD. with .109 inchwall was attached to a standard port fitting installed in a solid base.The tube was positioned horizontally and loaded on the end with a fixedweight (cantilever beam). Stress in the tube was calculated from strainmeasurements at the ferrule and at the outer end of the Special nut (1%)13,200

Comparative tube stress at the outer end of the nut (same conditions asabove):

P.s.i.

Production nut (2 1 8,370

Special nut (1%") Special nut (1%") 12,450

(ill

The indication is that a still longer nut would result in furtherdecrease in stress at the ferrule. Nut length however cannot beincreased appreciably beyond the present length because of spacelimitations on the tube.

Although a spherical connection is shown, a flare or any othermetal-to-metal rigid connection is anticipated as within the scope ofthe present disclosure.

Having described a preferred form of the invention, it will be realizedthat other embodiments will become readily apparent to those skilled inthe art within the scope of the appended claims.

What is claimed is:

1. A high pressure coupling between a hydraulic component subject tovibration having a metal conduit rigidly connected thereto, thecombination comprising a fluid carrying metal tube, a sleeve rigidlyattached to said conduit at one end, a substantially conical terminalface on said sleeve opposing a similarly but oppositely sloped terminalend on said conduit, said sleeve encompassing the terminal end of saidtube in space relation thereto about its entire periphery, [an] ametallic enlargement rigidly formed on the outer periphery of theterminal end of said tube and having sloping faces thereon complementaryto said opposing faces of the sleeve and conduit and rigidly heldthereby in fluid-tight adjusted position, adjustable clamping means onthe opposite end of said sleeve, a gasket of resilient material disposedabout the outer periphery of the tube and held between said clampingmeans and an end face of the sleeve at said opposite end thereof incushioning relation between the tube and sleeve whereby to absorbvibration shocks imposed on the coupling and thereby reduce the loads onthe coupling to an acceptable level, said gasket being spaced from theenlargement between the center lines thereof a distance equal to no lessthan one and one half [to two] outer diameters of said tube.

2. The invention according to claim 1 and said distance being betweenone and one half and approximately two outer diameters of said tube.

References Cited The following references, cited by the Examiner, are ofrecord in the patented file of this patent or the original patent.

UNITED STATES PATENTS 1,942,213 1/1934 Howard 285143 2,422,597 6/1947Stewart 285116 2,677,557 5/1954 Worel 285-15 3,264,014 8/1966 Brown285133 FOREIGN PATENTS 217,256 9/1961 Austria.

63,357 6/1949 Netherlands. 292,513 8/1953 Switzerland.

DAVE W. AROLA, Primary Examiner US. Cl. X.R.

